(The author might run off)
After an intense battle between the hero and the Demon Lord, they are forced to merge (seriously).
They can only share one body and the same senses.
Including, but not limited to, sight, hearing, and touch.
From then on, they level up together, travel together, sleep together, and even... hit on girls together?
"Stop hitting on girls already!!! If you're the hero, hurry up and save the world! I never want to experience kissing a girl again... I'm not a lesbian!"
The Demon Lord, Lady Lilith, is scolding him again today.